Add t-echo plus support

variants/nrf52840/t-echo-plus/variant.cpp

@@ -0,0 +1,24 @@
+#include "variant.h"
+#include "nrf.h"
+#include "wiring_constants.h"
+#include "wiring_digital.h"
+
+const uint32_t g_ADigitalPinMap[] = {
+    // P0 - pins 0 and 1 are hardwired for xtal and should never be enabled
+    0xff, 0xff, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+
+    // P1
+    32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47};
+
+void initVariant()
+{
+    // LEDs (if populated)
+    pinMode(PIN_LED1, OUTPUT);
+    ledOff(PIN_LED1);
+
+    pinMode(PIN_LED2, OUTPUT);
+    ledOff(PIN_LED2);
+
+    pinMode(PIN_LED3, OUTPUT);
+    ledOff(PIN_LED3);
+}